This is a project to acquire more information about the action of general and local anesthetics at the cell membrane level. The medium for this work is the model cell membrane or lipid bilayer. This model membrane will be investigated with regard to its change in dimension and state with application of a general anesthetic agent halothane or local anesthetic lidocaine. The membrane will also have incorporated into its substances to allow ion conductivity. This will also be investigated with regard to anesthetic effect. Finally, the membrane will be made active by incorporating materials which give a voltage dependent ion conductivity as seen in nerve. In these systems the effects of the anesthetic agents will be measured. The purpose of these experiments is twofold. The first is to gain more information on the membrane effects of general and local anesthetic to elucidate their mode of action. The second is to test the theories of anesthesia which have been proposed. The theories of local anesthesia break down into two categories. One proposes a unitary idea that local anesthetics act by the same unknown mechanism as general anesthetics at the membrane level. The other proposes some specific interaction with nerve. In the model system the local anesthetic can be observed to have an effect or not and this may be compared with that seen for a general anesthetic agent. Because there are none of the postulated nerve receptors in this system, this can test whether the local anesthetic is effective under these circumstances and whether its effect is similar to that of a general anesthetic. The theories of general anesthesia postulate that the membrane changes, fluidizing or other, lead to a change in the ability of membrane constituents to assume their active form. By looking at an active process in the model membrane, the inhibition by anesthetic will be checked to see if there is indeed a general process.